Study on self-healing ability of UHPC exposed to high temperature
Ultra-High Performance Concrete(UHPC)has a broad application prospect in engineering con-struction with its superior mechanical properties and durability performance.However,UHPC has a dense internal structure and poor high temperature resistance,and its performance in all aspects decreases signifi-cantly after exposure to high temperature environment,which limits its application in structural engineering and underground construction.This study aims to investigate the self-healing ability of UHPC after exposure to high temperature environment.UHPC is prepared using cement-fly ash-silica fume cement ma-trix and steel fiber design,with polypropylene fiber blended to enhance high temperature resistance.The self-healing ability of UHPC after high-temperature exposure was evaluated by simulating the exposure in the subsurface environment.The self-healing ability was characterized by measuring the changes in compres-sive strength,flexural strength and crack width before and after the high temperature exposure and after the self-healing test.The effect of self-healing tests on UHPC fracture toughness was characterized by fracture opening displacement(CMOD)tests and digital image correlation(DIC)methods.It was found that the self-healing effect of the groundwater environment restores the stiffness and tensile strength of UHPC,as well as the healing of high-temperature cracks.Meanwhile,the recovery of compressive strength was mini-mal due to corrosion of steel fibers.This study can provide a solid basis for broadening the application fields of UHPC.
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